Abstract : The report covers a study of the corrosion resistance provided by specification finishing systems to aluminum and magnesium exposed in a tropical environment. These systems include chemical, anodic, and wash primer metal pretreatments and primers specified for these metals in Military Standard No. 171 'Finishing of Metal and Wood Surfaces'; several other specification primers that have been used for these metals and an experimental epoxy primer. Finish coats included specification lustreless, semi-gloss, and gloss alkyd resin enamels and gloss polyamide-epoxy enamel. Test specimens were exposed in the Panama Canal Zone at rain forest and sea coast sites. After 26 months exposure, data show numerous specification finishing systems are available to provide corrosion resistance for aluminum and magnesium. The duration of this protection remains to be determined by additional exposure of the more effective systems. (Author)